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net: fec: ERR007885 Workaround for XDP TX path

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The ERR007885 will lead to a TDAR race condition for mutliQ when the
driver sets TDAR and the UDMA clears TDAR simultaneously or in a small
window (2-4 cycles). And it will cause the udma_tx and udma_tx_arbiter
state machines to hang. Therefore, the commit 53bb20d1faba ("net: fec:
add variable reg_desc_active to speed things up") and the commit
a179aad12bad ("net: fec: ERR007885 Workaround for conventional TX") have
added the workaround to fix the potential issue for the conventional TX
path. Similarly, the XDP TX path should also have the potential hang
issue, so add the workaround for XDP TX path.

Fixes: 6d6b39f180b8 ("net: fec: add initial XDP support")
Signed-off-by: Wei Fang <wei.fang@nxp.com>
Link: https://patch.msgid.link/20251128025915.2486943-1-wei.fang@nxp.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
This commit is contained in:
Wei Fang 2025-11-28 10:59:15 +08:00 committed by Paolo Abeni
parent 8f7aa3d3c7
commit e8e032cd24
1 changed files with 6 additions and 1 deletions
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7
drivers/net/ethernet/freescale/fec_main.c
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@ -3933,7 +3933,12 @@ static int fec_enet_txq_xmit_frame(struct fec_enet_private *fep,
txq->bd.cur = bdp;
/* Trigger transmission start */
writel(0, txq->bd.reg_desc_active);
if (!(fep->quirks & FEC_QUIRK_ERR007885) ||
!readl(txq->bd.reg_desc_active) ||
!readl(txq->bd.reg_desc_active) ||
!readl(txq->bd.reg_desc_active) ||
!readl(txq->bd.reg_desc_active))
writel(0, txq->bd.reg_desc_active);
return 0;
}